The Global Map of Vitamin D Deficiency

Despite common assumptions that sunny climates ensure adequate Vitamin D, a global analysis reveals a different reality. The Eastern Mediterranean region records the highest deficiency rate worldwide, with 35.2% of its population falling short of this essential nutrient.

Global Vitamin D Deficiency: Regional Overview

A comprehensive analysis of 7.9 million individuals, published in Frontiers in Nutrition, mapped Vitamin D deficiency across all World Health Organization (WHO) regions. The findings challenge the notion that ample sunlight guarantees sufficient Vitamin D levels.

The regions with the highest rates of deficiency are:

• Eastern Mediterranean: 35.2%
• South-East Asia: 22.0%
• Europe: 18.0%

Other regions show lower, but still significant, rates:

• Western Pacific: 10.0%
• Africa: 8.0%
• The Americas: 5.5%

Globally, 15.7% of people are deficient, and nearly half (47.9%) fall below healthy Vitamin D levels. This means an individual in the Eastern Mediterranean region is over six times more likely to be deficient than someone in the Americas.

South Asia's Paradox: High Sun, High Deficiency

When examining individual countries, South Asia stands out for its high rates of Vitamin D deficiency, despite abundant year-round sunshine. The region's overall deficiency rate for adults is 68%, affecting roughly two in every three people.

Specific country rates in South Asia include:

Pakistan's rate is 25 percentage points higher than Sri Lanka's, highlighting significant disparities even within the region. Women in South Asia are disproportionately affected, with 76% low in Vitamin D compared to 51% of men.

Latitude, Season, and Skin Tone: Key Influencers

The data reveals that Vitamin D deficiency does not simply increase with distance from the equator. People living between 20° and 40° north latitude—a band encompassing North Africa, the Middle East, South Asia, and southern China—exhibit the highest rate at 23.1%.

Surprisingly, moving farther north to 40°–60° latitude sees the rate drop to 14.9%, and above 60° north, closer to the Arctic, it falls to 10.4%. Near the equator, rates are 5.9% just north and 1.5% just south. This suggests that factors like heat keeping people indoors, extensive clothing coverage, and darker skin tones requiring longer sun exposure contribute to higher deficiency in sun-drenched middle latitudes.

Seasonal variations also play a crucial role. A national nutrition surveillance study in Iran found that 90.1% of participants were deficient in winter, a figure that dropped to 69.2% in summer. This seasonal swing resulted in average blood levels rising by over 60% from winter to summer. Globally, deficiency in winter and spring is 1.7 times higher than in summer and autumn.

Even high-income countries with access to fortified foods and supplements show notable differences:

• Germany: 15.2% deficient
• Ireland: 12.3% deficient
• Canada: 8.8% deficient
• United States: 5.0% deficient
• Australia: 4.5% deficient

Germany's rate is more than three times Australia's, influenced by latitude, cloud cover, and the extent of food fortification. Beyond outright deficiency, 18.3% of Americans and 29.4% of Canadians sit just above the deficiency line, while 40.4% of Europeans fall short of healthy levels. Skin tone is another critical factor; in the United Kingdom, 19.6% of white participants were deficient, compared with 59.6% of Asian participants.

Demographic and Economic Patterns

Vitamin D deficiency does not affect all demographics equally. Women globally show a deficiency rate of 17.8%, making them approximately 30% more likely to be deficient than men, who have a rate of 13.6%.

Age also presents an interesting pattern:

• Adults aged 19 to 44: 18.2% (highest rate)
• Adults aged 45 to 64: 13.8% (lowest rate)
• Adults aged 65 and over: 15.3%

This suggests that younger working-age adults are more prone to deficiency than older adults, contrary to common expectations.

Income levels also correlate with deficiency rates:

• Lower-middle-income countries: 26.7% (highest rate)
• High-income countries: 15.1%
• Low-income countries: 14.8%
• Upper-middle-income countries: 10.2% (lowest rate)

Upper-middle-income nations perform best, even surpassing high-income countries. Lower-middle-income countries, by contrast, show a rate more than two and a half times higher. Encouragingly, global deficiency rates have improved, falling from 17.6% between 2000–2010 to 14.1% between 2011–2022, a 3.5 percentage point drop over two decades.

Disclaimer: This article provides general information and statistics based on the source material. It is not intended as medical advice. Consult with a healthcare professional for personalized health guidance.

This article is general information only and is not legal or tax advice. Consult a licensed professional in your jurisdiction before acting on residency, incorporation, or tax topics.